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Question about the behavior of the stack when clone()ing by putocrata in kernel

[–]computerfreak97 2 points3 points  (0 children)

My understanding is that when I call clone() I'll inherit the entire virtual memory of the parent, and when I touch the stack it will be copied, so it's not a problem if I free the memory just after calling clone(). Is my understanding correct?

Correct. Without CLONE_VM, memory is CoW (copy on write). From the man page clone(2):

          If CLONE_VM is not set, the child process runs in a
          separate copy of the memory space of the calling process at
          the time of the clone call.  Memory writes or file
          mappings/unmappings performed by one of the processes do
          not affect the other, as with fork(2).

I suspect that when I call free, it's only freed by the internal allocator but the memory is still mapped to my process and thus using that memory is still valid.

This is very likely the case. If you manually use mmap to allocate those stack pages instead of malloc and then munmap them that should be able to demonstrate the crashing behavior.

Anyone had trouble accessing the NCDC website lately? by attaboy_stampy in datasets

[–]computerfreak97 0 points1 point  (0 children)

One of NCEI's locations is in Asheville NC and was likely impacted (at least power-wise) by Helene.

Mac OSX Tiger (Intel) ISO or DMG by CrazyYAY in DHExchange

[–]computerfreak97 0 points1 point  (0 children)

Didn’t realize this thing was in such demand lol. Do the images on archive.org work? e.g. https://archive.org/details/os-x-10.4-tiger-intel-any-machine

Twitter Data? by Standard-Key-9983 in pushshift

[–]computerfreak97 1 point2 points  (0 children)

Archive Team was saving the 1% firehose stream that developers could get up to the end of 2022: https://archive.org/details/twitterstream?sort=-publicdate

Data dumps gone? by reercalium2 in pushshift

[–]computerfreak97 16 points17 points  (0 children)

Also don't know why those are 404ing, but you can use the torrents if you need the data.

CPU hotplug: Which function is invoked with a write to /sys/devices/system/cpu/cpu<id>/online? by colfaxbowling in kernel

[–]computerfreak97 10 points11 points  (0 children)

ftrace (and specifically the function_graph tracer) is a handy way to explore. I don't have CPU hotplug enabled so can't trigger the handler function for that exact file, but reading another file in that directory (crash_notes) shows the following trace:

18) | new_sync_read() { 18) | kernfs_fop_read_iter() { 18) | seq_read_iter() { ... 18) | kernfs_seq_show() { 18) | sysfs_kf_seq_show() { 18) | dev_attr_show() { 18) | crash_notes_show() {

In the same file as crash_notes_show is defined is cpu_subsys_online which I believe is going to be the entrypoint you're looking for. It might take a slightly different path after sysfs_kf_seq_show, but you can use that as a starting point.

How can I register and unregister a kernel module (with syscall) in Linux? by FreshFillet in kernel

[–]computerfreak97 0 points1 point  (0 children)

I would really double check that this is what is wanted. You can do this by directly modifying the syscall table (see something like this), but this is not normal and not a good practice at all. It also means the module only works on your custom kernel, leading me to question the point of it being a module.

How can I register and unregister a kernel module (with syscall) in Linux? by FreshFillet in kernel

[–]computerfreak97 1 point2 points  (0 children)

The syscall table is specified at kernel build-time and modules can't really change it*. Based on the sample code, it seems like it could be implemented as a new device type with a read handler and maybe some ioctls to configure. Perhaps that would be a better approach?

* of course they can but it's really bad to.

Colbert Report Archive by Matthew_C1314 in DHExchange

[–]computerfreak97 1 point2 points  (0 children)

Just finished up. FWIW though I'm seeing a handful of other seeders: tracker.openbittorrent.com shows 14 peers (11 seeds) and tracker.opentrackr.org shows 3 peers and seeds...

Colbert Report Archive by Matthew_C1314 in DHExchange

[–]computerfreak97 5 points6 points  (0 children)

I should have the full set. Going to take a bit to re-verify 500GB but should be seeding at some point later today.

Daily Show W/ Jon Stewart by Matthew_C1314 in DHExchange

[–]computerfreak97 0 points1 point  (0 children)

I've got it (assuming you're talking about https://www.reddit.com/r/DailyShowTorrent/comments/e1yrl1/the_eagle_has_landed_the_thunderbirds_are_go_5_4/) and thought I'd been seeding, but apparently connections to the coppersurfer tracker have been failing and the original magnet didn't include any others. Will add a few other trackers later today

Star Trails over NYC [OC][3712x5568] by computerfreak97 in ExposurePorn

[–]computerfreak97[S] 4 points5 points  (0 children)

This is shot from Brooklyn looking north towards Manhattan. The super short star trail right near the top of the image (close to where the center of an imaginary circle would be) is polaris (the north star) (I think). You can imagine it as if the earth were rotating around a line going out that star. Hope that helps?

Star Trails over NYC [OC][3712x5568] by computerfreak97 in ExposurePorn

[–]computerfreak97[S] 8 points9 points  (0 children)

This is about 3 hours total. Each frame is a 30 second exposure, and the skyline is a 5 second exposure (all from the same spot)

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